Field of Invention
The present invention relates to an implant. More particularly, the present invention relates to an auricular implant.
Description of Related Art
According to the statistics, the incidence rate of the microtia is 1/5000- 1/6000 in Asia and 1/7000 in the world. The incidence rate of the unilateral (one side only) microtia is 6 times of that of the bilateral (both sides) microtia; and there are twice as many right-sided microtias than left-sided microtias. For the unilateral microtia patient, it is desirable to reconstruct a prosthetic ear having similar shape with the normal ear. However, the sizes, the shapes and the outlines of the ears of patients are different, so the commercial available prosthetic ears having only few sizes, shapes and outlines cannot fit the normal ears of different patients well. Hence, it is desirable to provide a flexible and adjustable implant, which can fit the normal ears of different patients well.
In addition, the microtia occurs when the auricle is formed in the embryonic period. Approximately from the third week of the embryogenesis, the embryonic cell in the ectoderm has pathological changes, resulting in arrested development of external ear, which is referred to as the microtia in clinical. The clinical symptom of the microtia is mainly the defect of the auricular appearance in addition to the hearing abnormity. Thus, the microtia patient usually requires an auricular reconstruction. Besides, for the patient who has a severe trauma on his/her head, the auricular reconstruction is also necessary.
Currently, there are three common ways of the auricular reconstruction. The first way is wearing an ear model; the second way is using a medpor; and the third way is using an autogenous cartilage graft for reconstruction. The auricular reconstruction with autogenous cartilage is the top choice in the clinical. However, a two-stage surgery is required for the autogenous costal cartilage reconstruction. In the first stage in which the auricular model is plane rather than stereo, the patient's costal cartilage is taken out, carved into the shape of the ear bone, and then implanted subcutaneously. The second stage of the surgery is performed about six months later after the first stage. The surgeon raises the ear flap and implants the above auricular model, and then the auricular model is formed as a stereo ear. It is very difficult to employ this method. Besides, this method is suitable for the auricular reconstruction only when the patient's thorax is developed to above 60 cm or when the patients are over ten years old. Furthermore, the region where the costal cartilage is taken out will cause severe pain for 3 to 4 days after the surgery and also leave a scar. The living quality of the patient will be seriously affected in one month after the surgery.
In recent years, due to the improvement of medical materials, people place high hopes on the artificial materials, which may be the second best choice compared to the autogenous cartilage. Moreover, owing to the convenience of artificial materials in the clinic without complex carving techniques, some surgeons have already used the first way and the second way of reconstruction. In the first way, an externally hang-type prosthetic ear is used, wherein silicone is used to form the ear model, and a bone nail is implanted at the corresponding position of the ear to hang the silicone ear model; however, the externally hang-type prosthetic ear needs to be replaced every 2 to 5 years, and the bone nail requires a life-long maintenance to prevent the bone nail from piercing the skin. Thus, the first way is not the top choice.
In the second way, a Medpor® implant is used, but its flexibility is not good enough and it is easily broken after the reconstruction surgery. Referring to U.S. Pat. No. 5,433,748, an auricular implant is described. The material of the auricular implant is an elastic and porous polyethylene, which forms a structure including an auricular framework and a spiral skeleton. However, this auricular implant is a plane model such that it cannot be supported during the reconstructive surgery process, and after the surgery, it may not look like the naturally developed auricle in appearance very much. Furthermore, since the material of this auricular implant is thermoplastic polyethylene, it is necessary to provide certain temperature to change the auricular appearance. Besides, the material is hard and the plasticity and elasticity is finite. As a result, patient's skin may be wounded or the implant may be exposed due to collision, extrusion or thinning of ear skin caused by the implant, resulting in deformation of the auricular appearance.
Thus, the main task in the industry is how to prepare the auricular implant that looks more like the naturally developed auricle from the artificial material.